Detection apparatus for detecting sector marks of optical disk and optical disk access apparatus

Abstract

A sector mark detection apparatus detects a sector mark added to an arbitrary sector of an optical disk when seeking the arbitrary sector, where the optical disk has a predetermined recording format in which a predetermined number of sectors are arranged on the optical disk. The sector mark detection apparatus is provided with a gate signal generating circuit for generating a predetermined number of gate signals at predetermined intervals based on timings between pulse signals which are read from the optical disk, a mark length generating circuit for generating mark length data related to lengths of the sector marks from the read pulse signals based on the timings, a counter circuit for measuring widths of the gate signals by counting at a predetermined frequency and for outputting counted values, a matching circuit for comparing the counted values and match data and for outputting a matched result, and a judging circuit for judging the sector mark of the arbitrary sector based on the mark length data and the matching result.

What is claimed is: 
     
       1. A sector mark detection apparatus which detects a sector mark added to an arbitrary sector of an optical disk when seeking the arbitrary sector, said optical disk having a predetermined recording format in which a predetermined number of sectors are arranged on the optical disk, said sector mark detection apparatus comprising: gate signal generating means for generating a predetermined number of gate signals at predetermined intervals based on timings between pulse signals which are read from the optical disk;   mark length generating means, coupled to said gate signal generating means, for generating mark length data related to lengths of the sector marks from the read pulse signals based on said timings;   counter means, coupled to said gate signal generating means, for measuring widths of the gate signals by counting at a predetermined frequency and for outputting counted values;   matching means, coupled to said counter means, for comparing the counted values and match data and for outputting a matched result; and   judging means, coupled to said matching means, for judging the sector mark of the arbitrary sector based on the mark length data and the matching result.   
     
     
       2. The sector mark detection apparatus as claimed in claim 1, wherein said gate signal generating means includes: a ring counter generating timing signals corresponding to the timings between the pulse signals read from the optical disk based on the pulse signals; and   a gate signal generating circuit generating the gate signals based on the timing signals.   
     
     
       3. The sector mark detection apparatus as claimed in claim 1, wherein said matching means includes a match data generating circuit generating the match data corresponding to the sector marks for each of zones of the optical disk. 
     
     
       4. The sector mark detection apparatus as claimed in claim 1, wherein said judging means judges that the sector mark of the arbitrary sector has been detected if a datum of the matching result is related to the arbitrary sector and matches a bit rate indicated by the mark length data. 
     
     
       5. The sector mark detection apparatus as claimed in claim 1, wherein the optical disk has a recording format in conformance with a MCAV (Modified Constant Angular Velocity) system.